Packer with spring biased threaded slips



United States Patent 3,136,365 PACKER WITH SPRING BIASED TADED SLIPS Thomas J. Carter, San Marine, and James C. Williams, Anaheim, Calif., assignors to Baker Gil Tools, Inc., Los Angeies, Caliti, a corporation of California Filed Get. 9, 1961, Ser. No. 143,646 18 Claims. (Cl. 166-136) The present invention relates to subsurface well bore apparatus, and more particularly to anchors or packers adapted to be set in a well bore for the purpose of performing certain desirable operations therein, such as cementing, acidizing, producing, formation fracturing,

testing or bridging.

An object of the present invention is to provide an improved subsurface well bore apparatus having normally retracted elements, such as normally retracted slips or a normally retracted packing structure, or the like, which are positively held initially in retracted position to prevent their inadvertent outward expansion, and which can be readily released when desired and easily expanded outwardly against the wall of the confining well bore or well conduit disposed in the well bore.

Another object of the invention is to provide a subsurface well tool embodying slips which are held initially in a retracted position by a protecting member encompassing the slips, such member being released from its encompassing position in an easy manner to allow outward expansion of the slips.

A further object of the invention is to provide a subsurface well tool embodying slips which are held initially in a retracted position and which will resist substantial longitudinal forces encountered in the well bore tending to expand the slips, the slips being readily released from their retracted position and easily expanded outwardly.

- An additional object of the invention is to provide a subsurface well tool embodying slips, such as a well packer, the slips being positively held in a retracted position and readily released for outward expansion, the slips being of a simplified design, strong and'sturdy in construction, and relatively economical to manufacture.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specification. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE 1 is a side elevation and longitudinal section of a well apparatus in a well casing, with the apparatus parts in an initial, retracted position;

FIG. 2 is an enlarged longitudinal section of the apparatus shown in FIG. 1, with certain parts in another relative position;

FIG. 3 is a view similar to FIG. 2, with the apparatus fully set in the well casing;

FIG. 4 is an enlarged cross-section taken along the line 44 on FIG. 1; and

FIG. 5 is an enlarged longitudinal section taken along the line 55 on FIG. 4.

The apparatus A illustrated in the drawings can function as a well packer adapted to be anchored in packedofi condition in a well casing B, or similar conduit string, disposed in a well bore and is prefereably of the type that can be used for well production purposes. It is run in the well casing B, or similar conduit string, on a setting mandrel C, the upper portion of which is attached to the lower end of a tubular running-in string D, such as tubing or drill pipe, extending to the top of the hole.

The well packer A includes a tubular body 10 having an upper threaded box 11 adapted to threadedly receive a companion nut 12 mounted on the setting mandrel C, which is disposed within the central bore 13 of the body, a suitable side seal structure 14 being mounted on the mandrel for sealing against the wall of the body. The setting nut 12 is movable longitudinally on the mandrel C, but is prevented from rotating therewith by virtue of a key 15 suitably secured to the mandrel and slidably received Within a longitudinal groove 16 in the nut.

When in a lower position on the mandrel, the nut 12 engages a suitable upwardly facing mandrel shoulder .17, the nut being capable of shifting upwardly on the mandrel against the force of a helical compression spring 13 bearing against a mandrel shoulder 19 and against the upper end of the nut.

The packer body 19 includes an enlarged upper head portion 20 providing a downwardly facing shoulder 21 and a lower guide 22 providing an upwardly facing shoulder 23. Surrounding the upper head is a setting sleeve 24 having an inwardly directed shoulder or flange 25 disposed under the body shoulder 21 and also a depending skirt 26 spaced outwardly from the periphery of the body. A set of upper segmental slips 27 is disposed around the upper portion of the body, these slips having recesses 28 in their upper outer portions 29 so that the latter can be received within the skirt 26, which will hold the slips in an inward or retracted position against the body 19, with internal threads 30 formed on the slips meshing with companion external threads 31 of the packer body 10. When the threads 30, 31 are fully meshed with one another, the slips 27 are disposed upwardly to their fullest extent within the setting sleeve skirt 26, which holds the slips meshed with the body thread 31 (FIG. 1). The body 10, however, can be turned with respect to the slips 27, to relatively feed the slips downwardly along the body until the threaded portion 30 of the slips becomes disconnected from the body thread 31. Thereafter, relative longitudinal movement between the body 10 and slips 27 can occur without rotating the body, as described hereinbelow.

Relative movement between the body 10 and the slips 27 can be effected since both longitudinal movement and rotation of the setting sleeve 24 and of the slips 27 confined within the skirt 26 are resisted by a drag device 33. As specifically shown, this drag device consists of circumferentially spaced outwardly bowed springs 34 adapted to frictionally engage the wall of the well conduit B. These springs are preferably received within longitudinal grooves 35 in the exterior of the setting sleeve, the upper free ends 36 of the springs riding upon the bases of the grooves 35, the lower ends of the springs having inwardly directed portions 37 received within a groove 38 in the setting sleeve. A retainer ring 39 surrounds the lower portions 37 of the outwardly bowed drag springs, to hold them assembled against and in the sleeve 24, removal of the ring from the sleeve being prevented by the attaching screws 40 threaded into the sleeve.

The upper segmental slips 27 have upwardly facing wickers or teeth 41 adapted to embed themselves in the wall of the well casing B when the slips are expanded outwardly thereagainst. They also have inner surfaces 42 tapering in an upward and inward direction and adapted to engage a companion externally tapered surface 43 on an upper expander 44 initially releasably secured to the body 10 of the tool by one or more shear screws 45. Surrounding the body is a packing structure 46, such as a packing sleeve of rubber or rubber-like material, disposed initially in a retracted position, with its upper end engaging the upper expander 44 and its lower end engaging a lower expander 47 secured initially to the packer body by one or more shear screws 48. This lower expander has an external expander surface 49 tapering downwardly and inwardly and engaging companion inner tapered surfaces 50 on a lower set of segmental slips 51 held initially in retracted position by shear screws 52 attaching them to the lower expander. These lower slips have downwardly facing wickers or teeth 53 adapted to engage the wall of the well casing when expanded outwardly thereagainst by the lower expander 47. Initially, the lower slips 51 rest upon the upwardly facing shoulder 23 provided by the body guide 22.

As set forth above, the upper set of slips 27 is retained initially in the retracted position by the depending setting sleeve skirt 26 that encompasses them and which holds them in full threaded mesh with the body thread 31. Unthreading of the body 10 from the slips 27 results from rotating the tubular string D and the mandrel C, this rotation being transferred through the threaded nut 12 to the body 10 of the tool. Rotation of the slips 27 is prevented by longitudinally extended keys 55 which are suitably secured in the skirt portion 26 of the setting sleeve, as by brazing them thereto, the keys extending downwardly into the gaps or spaces 56 between the upper slips. Thus, the upper slips 27 engage the keys 55 to prevent turning of the slips relative to the setting sleeve 24, rotation of the setting sleeve being prevented by the frictional engagement of the drag springs 34 against the wall of the well casing B.

When the slips 27 are unthreaded from the body 16 and are moved relatively downwardly out of the encompassing setting sleeve skirt 26, they are expanded outwardly by a spring device. As shown, an outwardly expansible spring member 58, in the form of a coil spring made of flat material, is disposed around the body 10 of the tool and is received within an internal groove 59 formed collectively in the slips 27. This spring 58 may have more than one turn, and inherently tends to uncoil or unwind to expand the slips 27 outwardly against thewall of the well casing B. Such outward expansion can only occur when the upper portions 29 of the slips have been moved relatively downwardly below the encompassing setting sleeve skirt 26. The spring 58 not'only urges the slips outwardly into engagement with the wall of the well conduit, but it also serves to hold the slip segments in transverse alignment by engaging the upper and lower walls of the internal groove 59 in the slips 27.

After the slips 37, 51 and packing 46 have been expanded against the wall of the well casing B, as explained hereinbelow, they are held in their expanded position by a suitable one-way lock device. As shown, the body 10 of the tool has circular ratchet teeth 60 thereon facing in a downward direction and adapted to engage companion internal ratchet teeth 61 in a split ratchet sleeve 62 mounted in the upper expander 44. The exterior of the ratchet sleeve is formed with cam teeth 63 adapted to coact with companion cam teeth 64 on the upper expander 44. Accordingly, it is apparent that the ratchet teeth 60, 61 permit upward movement of the body 10 relative to the upper expander 44, but preclude downward movement relative thereto, since such downward movement will cause the ratchet teeth 60, 61 to coengage and the cam teeth 63, 64, whose cam surfaces taper in a downward and inward direction, will force the ratchet sleeve 62 inwardly to retain the ratchet teeth 60, 61 in engagement with one another.

Initially, the upper slips 27 are disposed within the skirt 26 of the setting sleeve 24 and are in full threaded mesh with the thread 31 of the packer body 10, the threaded connection 30, 31 between the body and slips preferably being left hand. The upper expander 44 and lower expander 47 are suitably secured to the body of the well packer by their respective shear screws 45, 48, the lower shear screws 52 holding the lower slips 51 in their retracted position (FIG. 1). It is to be noted that the upper slips 27 preferably are spaced upwardly relative to the upper expander 44, so as to permit the upper slips to move downwardly along the body 10 in connection with their unthreading from the body thread 31 to an extent sufficient to bring the upper portions 29 of the slips completely out of the encompassing setting sleeve skirt 26, allowing the coil spring 58 to expand the slips 27 against the wall of the well conduit B.

The nut 12 of the setting mandrel C is threaded into the packer box 11 to its fullest extent and the mandrel secured to the tubular string D, by means of which the well packer A is lowered in the well casing B, or other conduit string, to the desired setting point. When such location is reached, the tubing string D and mandrel C are turned to rotate the body 10 of the well packer and all parts connected thereto. However, the upper slips 27 and setting sleeve 24 do not rotate, because of the frictional resistance to turning offered by the drag springs 34 against the wall of the well casing B. The turning of the tubular string C and the body 10 of the tool to the right will result in a relative downward feeding of the upper slips 27 and the drag device along the body 10 of the tool, or a relative upward movement of the body 10 of the tool along the slips 27. Such relative feeding will occur upon turning of the body 10 a sufiicient number of turns (for example, seven turns) until the slips 27 are threadedly disconnected from the body 10. At this time, the lowermost thread turn 31a on the body 10 is disposed above the uppermost thread turn 30a on the slips, the slips themselves still being disposed within the head skirt 26. The tubular string D and body 10 of the tool may now be moved downwardly to cause the body thread turn 31a to engage the slip thread turn 30a and shift the slips 27 downwardly out of the setting sleeve skirt 26, downward movement of the setting sleeve 24 being resisted and prevented by the frictional engagement of the drag springs 34 against the wall of the well casing. When the upper portions 29 of the slips are disposed below the skirt 26, the coil spring 58 can and will expand, to expand the slips 27 outwardly against the wall of the well casing (FIG. 2).

The tubing string D and packer body 10 may now be elevated to bring the upper expander 44 upwardly and wedge it behind the slips 27. Upward movement of the slips is prevented by their wickers 41 engaging the wall of the well casing B. Their upward movement may also be resisted by engagement of the upper portions 29 of the slips with the lower end of the setting sleeve skirt 26 (FIG. 2), upward movement of the setting sleeve 24 being resisted by the frictional engagement of the drag springs 34 against the wall of the well casing. The upper expander 44 will wedge behind the upper slips 27, precluding further upward movement of the expander 44. A suflicient strain is taken on the tubular string D and body 10, which is transferred through the mandrel shoulder 17 and nut 12 to the body 18, to shear the screws 45 holding the upper expander 44 to the body; whereupon the body moves upwardly to shift the lower expander 47 toward the upper expander 44, shortening the packing element 46 and expanding it outwardly against the wall of the well casing B. A continuation of the upward strain on the tubular string D, mandrel C and body 10 will also result in shearing of the screws 48, 52 holding the lower expander 47 to the body and the lower slips 51 to the lower expander, the lower guide 22 then shifting the lower slips 51 along the expander 47 and outwardly into anchoring engagement with the wall of the well casing. A sufficient upward pull can now be taken on the tubular string D and body 10 of the tool to insure the full anchoring of the upper and lower slips 27, 51 against the well casing B and the proper and effective expansion of the packing element 46 into full sealing engagement with the wall of the well casing and with the periphery of the packer body 10 (FIG. 3).

As set forth above, the one-way lock device 60-64 will permit upward movement of the body 10 within the upper expander 44, but will preclude downward movement of the body within this expander. Upward movement will occur in connection with expanding the packing element 46 against the well casing B and the lower slips 51 against the well casing. Further upward movement is resisted by the wedging action of the upper expander 44 behind the upper slips Z7. Downward movement of the body 10 is prevented, since it is transmitted from the body through the lock ring 62 to the upper expander 44, and then through the packing element 46 to the lower expander 47, which wedges behind the lower slips whose wickers 53 are embedded in the wall of the well casing B.

Following the full setting in packed-01f condition of the well packer A against the wall of the Well casing B, the mandrel C can be released therefrom, if desired, as by rotating the tubular string D to the right, the mandrel rotating the nut 12 within the packer body It), with which it preferably has a left-hand threaded connection, the nut 12 moving upwardly along the mandrel until it is com pletely disconnected from the packer body box 11. If desired, the side seal 14 of the mandrel may remain in the bore 13 of the packer body, so that the tubular string 1) may be used for production purposes without removing it from the well bore, While yetpermitting limited movement of the tubular string D and mandrel C within the well bore relative to the packer body 15).

It is, accordingly, apparent that an apparatus has been provided in which normally retracted elements, such as the upper slips 27, are held positively in retracted position by the encompassing skirt 26 of the setting sleeve 24. Any longitudinal forces encountered in the well bore, as during the lowering of the well packer A therewithin, are incapable of inadvertently releasing and expanding the slips 27, because of their positive threaded connection 30, 31 with the packer body 10. It is only after the body It) has been rotated in the proper direction a sufiicient number of turns that the slips 27 thread downwardly relative to the body for disconnection therefrom; whereupon the slips 27 can be released from the encompassing skirt 26 and their outward expansion effected as well as wedging of the upper expander 44 therebehind to anchor the well tool A against upward movement in the well casing B. The upper slip segments 27 are comparatively simple in structure and can be produced in an economical manner. Following their outward expansion against the well casing, they resist upward movement by being engaged by the upper expander 44, because of the embedding action of their wickers 41 in the wall of the well casing. Initially, such upward movement is also resisted by engagement of the slips 27 with the lower end of the setting sleeve 26,

the upward movement of which in the well casing is resisted by the friction force of the drag springs 34' against the wall of the well casing. Setting of the well packer A in the well casing B is accomplished mechanically by manipulating the tubing string D and the body of the tool. The well packer A can thereafter be used for production purposes without removing the tubing string D from association therewith, the well production passing upwardly through the packer A and through the tubing string D to the top of the well bore.

We claim:

1. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on and shiftable with respect to said body and expandible laterally outwardly of said body; means releasably connecting said normally retracted means to said body to prevent longitudinal movement of said normally retracted means in both directions with respect to said body; means for shifting said normally retracted means laterally outwardly of said body; retainer means encompassing said normally retracted means to prevent said shifting means from shifting said normally retracted means; and means responsive to movement of the running-in string to release said connecting means and to relatively shift said retainer means and normally retracted means to remove said retainer means from encompassing relation to said normally retracted means and to permit said shifting means to shift said normally retracted means.

2. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on and shiftable with respect to said body and expandible laterally outwardly of said body; means releasably connecting said normally retracted means to said body to prevent longitudinal movement of said normally retracted means in both directions with respect to said body; spring means for shifting said normally retracted means laterally outwardly of said body; retainer means encompassing said normally retracted means to prevent said spring means from shifting said normally retracted means; and means responsive to movement of the running-in string to release said connecting meansand to relatively shift said retainer means and normally retracted means to remove said retainer means from encompassing relation to said normally retracted means and to permit said spring means to shift said normally retracted means.

3. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body including slip means shiftable with respect to said body and expandible laterally outwardly of said body; means releasably connecting said slip means to said body to prevent longitudinal movement of said slip means in both directions with respect to said body; shifting means for ex panding said slip means outwardly of said body; retainer means encompassing said slip means to prevent their outward expansion; and means responsive to movement of the running-in string and body to release said connecting means and relatively shift said retainer means and slip means to remove said retainer means from encompassing relation to said slip means and to permit said shifting means to expand said slip means.

4. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body including slip means shiftable with respect to said body and expandible laterally outwardly of said body; means releasably connecting said slip means to said body to prevent longitudinal movement of said slip means in both directions with respect to said body; spring means for expanding said slip means outwardlyof said body; retainer means encompassing said slip means to prevent their outward expansion; and means responsive to movement of the running-in string and body to release said connecting means and relatively shift said retainer means and slip means to remove said retainer means from encompassing relation to sail slip means and to permit said spring means to expand said slip means.

5. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body and expandible laterally outwardly of said body; means for shifting said normally retracted means laterally outwardly of said body; retainer means engaging said normally retracted means to prevent said shifting means from expanding said normally retracted means; said normally retracted means being threadedly connected to said body, whereby rotation of said body unthreads said normally retratced means from said body and allows disengagement of said retainer means from said normally retracted means to permit said shifting means to shift said normally retracted means; and means for resisting turning of said normally retracted means in the well bore to enable said body to rotate relative thereto.

6. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body and expandible laterally outwardly of said body; spring means for shifting said normally retracted means laterally outwardly of said body; retainer means engaging said normally retracted means to prevent said spring means from expanding said normally retracted means; said normally retracted means being threadedly connected to said body, whereby rotation of said body unthreads said normally retracted means from said body and allows disengagement of said retainer means from said normally retracted means to permit said spring means to shift said normally retracted means; and means for resisting turning of said normally retracted means in the well bore to enable said body to rotate relative thereto.

7. In Well apparatus adapted to be set in a Well bore: a body adapted to be lowered in the Well bore on a running-in string; normally retracted means on said body including slip means shiftable with respect to said body and expandible laterally outwardly of said body; means for shifting said slip means outwardly of said body; retainer means engaging said slip means to prevent said shifting means from expanding said slip means; said slip means being threadedly connected to said body, whereby rotation of said body unthreads said slip means from said body and allows disengagement of said retainer means from said slip means to permit said shifting means to shift said slip means; and means for resisting turning of said slip means in the well bore to enable said body to rotate relative thereto.

8. In well apparatus adapted to be set in a. well bore: a body adapted to be lowered in the well bore on a running-in string; slip means on said body and expandible laterally outwardly of said body; spring means for shifting said slip means laterally outwardly of said body; retainer means engaging said slip means to prevent said spring means from expanding said slip means; said slip means being threadedly connected to said body, whereby rotation of said body unthreads said slip means from said body and allows disengagement of said retainer means from said slip means to permit said spring means to shift said slip means; and means for resisting turning of said slip means in the well bore to enable said body to rotate relative thereto.

9. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body and expandible laterally outwardly of said body; means for shifting said normally retracted means laterally outwardly of said body; retainer means encompassing said normally retracted means to prevent said shifting means from expanding said normally retracted means; said normally retracted means being threadedly connected to said body, whereby rotation of said body unthreads said normally retracted means from said body allowing said retainer means to be removed from encompassing relation to said normally retracted means and to permit said shifting means to shift said normally retracted means; and means for resisting turning of said normally retracted means in the Well bore to enable said body to rotate relative thereto.

10. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body including slip means shiftable with respect to said body and expandible laterally outwardly of said body; means for shifting said slip means outwardly of said body; retainer means encompassing said slip means to prevent their outward expansion; said slip means being threadedly connected to said body, whereby rotation of said body unthreads said slip means from said body and allows said retainer means to be removed from encompassing relation to said slip means and to permit said shifting means to shift said slip means; and means for resisting turning of said slip means in the well bore to enable said body to rotate relative thereto.

11. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body including slip means shiftable with respect to said body and expandible laterally outwardly of said body; means releasably connecting said slip means to said body to prevent longitudinal movement of said slip means in both directions with respect to said body; a spring band behind and engaging said slip means to expand said slip means laterally outwardly; retainer means encompassing said slip means to prevent their outward expansion; and means responsive to movement of the running-in string and body to release said connecting means and relatively shift said retainer means and slip means to remove said retainer means from encompassing relation to said slip means and to permit said spring band to expand said slip means.

12. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on and shiftable with respect to said body and expandible laterally outwardly of said body; means releasably connecting said normally retracted means to said body to prevent longitudinal movement of said normally retracted means in both directions with respect to said body; means for shifting said normally retracted means laterally outwardly of said body; a sleeve encompassing said normally retracted means to prevent said shifting means from shifting said normally retracted means; resisting means on said sleeve adapted to engage the wall of the well bore to resist movement of said sleeve therewithin; and means responsive to movement of the running-in string and body to release said connecting means and to relatively shift said normally retracted means and sleeve to remove said sleeve from encompassing relation to said normally retracted means and to permit said shifting means to shift said normally retracted means.

13. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body including slip means shiftable with respect to said body and expandible laterally outwardly of said body; means releasably connecting said slip means to said body to prevent longitudinal movement of said slip means in both directions with respect to said body; means for expanding said slip means outwardly of said body; a sleeve encompassing said slip means to prevent their outward expansion; resisting means on said sleeve adapted to engage the wall of the well bore to resist movement of said sleeve therewithin; and means responsive to movement of the running-in string and body to release said connecting means and relatively shift said sleeve and slip means to remove said sleeve from encompassing relation to said slip means and to permit said expanding means to expand said slip means.

14. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body and expandible laterally outwardly of said body; means for shifting said normally retracted means laterally outwardly of said body; a sleeve encompassing said normally retracted means to prevent said shifting means from expanding said normally retracted means; resisting means on said sleeve adapted to engage the wall of the well bore to resist movement of said sleeve therewithin; said normally retracted means being threadedly connected to said body, whereby rotation of said body unthreads said normally retracted means from said body and allows disengagement of said sleeve from said normally retracted means to permit said shifting means to shift said normally retracted means; and means for resisting turning of said normally retracted means in the Well bore to enable said body to rotate relative thereto.

15. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body including slip means shiftable with respect to said body and expandible laterally outwardly of said body; means for shifting said slip means outwardly of said body; a sleeve on said body encompassing said slip means to prevent said shifting means from expanding said slip means; resisting means on said sleeve adapted to engage the wall of the well bore to resist movement of said sleeve therewithin; said slip means being threadedly connected to said body, whereby rotation of said body unthreads said slip means from said body and allows disengagement of said sleeve from said slip means to permit said shifting means to shift said slip means; and means for resisting turning of said slip means in the well bore to enable said body to rotate relative thereto.

16. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body including a set of segmental slips shiftable with respect to said body and expandible laterally outwardly of said body; a spring band behind and engaging said slips to expand said slips laterally outwardly; a sleeve on said body encompassing said slips to prevent said band from expanding said slips laterally outwardly; said slips being threadedly connected to said body and being maintained in threaded connection with said body by said sleeve; means keying said slips to said sleeve, whereby rotation of said body unthreads said body from said slips to permit said slips to be moved from their relation encompassed by said sleeve, whereupon said spring band can expand said slips laterally outwardly; and means on said sleeve for resisting movement of said sleeve in the well bore.

17. In well apparatus adapted to be set in a well bore: a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body including slip means shiftable with respect to said body and expandible laterally outwardly of said body; means releasingly connecting said normally retracted means to said body to prevent longitudinal movement of said normally a body adapted to be lowered in the well bore on a running-in string; normally retracted means on said body including a set of segmental slips shiftable with respect to said body and expandible laterally outwardly of said body, said slips having an inner groove extending circumferentially therearound; an expansible spring band within said groove engaging said slips to shift said slips laterally outwardly and to hold said slips in transverse alignment; retainer means engaging said slips to prevent said band from expanding said slips; and means responsive to movement of the running-in string and body to relatively shift said retainer means from engagement with said slips,

whereby said spring band can expand said slips laterally outwardly.

References Cited in the file of this patent UNITED STATES PATENTS 909,609 Kesselman Jan. 12, 1909 1,193,769 Cushing Aug. 8, 1916 1,653,547 Cameron Dec. 20, 1927 2,121,050 Ragan et a1 June 21, 1938 2,274,940 Stoddard Mar. 3, 1942 2,568,867 Otis Sept. 25, 1951 2,644,527 Baker July 7, 1953 3,013,611 Myers Dec. 19, 1961 

18. IN WELL APPARATUS ADAPTED TO BE SET IN A WELL BORE; A BODY ADAPTED TO BE LOWERED IN THE WELL BORE ON A RUNNING-IN STRING; NORMALLY RETRACTED MEANS ON SAID BODY INCLUDING A SET OF SEGMENTAL SLIPS SHIFTABLE WITH RESPECT TO SAID BODY AND EXPANDIBLE LATERALLY OUTWARDLY OF SAID BODY, SAID SLIPS HAVING AN INNER GROOVE EXTENDING CIRCUMFERENTIALLY THEREAROUND; AN EXPANSIBLE SPRING BAND WITHIN SAID GROOVE ENGAGING SAID SLIPS TO SHIFT SAID SLIPS LATERALLY OUTWARDLY AND TO HOLD SAID SLIPS IN TRANSVERSE ALIGNMENT; RETAINER MEANS ENGAGING SAID SLIPS TO PREVENT SAID BAND FROM EXPANDING SAID SLIPS; AND MEANS RESPONSIVE TO MOVEMENT OF THE RUNNING-IN STRING AND BODY TO RELATIVELY SHIFT SAID RETAINER MEANS FROM ENGAGEMENT WITH SAID SLIPS, WHEREBY SAID SPRING BAND CAN EXPAND SAID SLIPS LATERALLY OUTWARDLY. 